Climate and monthly weather forecastSaint Johns, IL
Climate and monthly weather forecast
Weather in January
January, like December, in Saint Johns, Illinois, is another cold winter month, with an average temperature fluctuating between 25.7°F (-3.5°C) and 38.8°F (3.8°C). In Saint Johns, January is the coldest month, with temperatures averaging a high of 38.8°F (3.8°C) and a low of 25.7°F (-3.5°C). Weather in January »Weather in February
February, the last month of the winter in Saint Johns, is a chilly month, with an average temperature ranging between min 29.5°F (-1.4°C) and max 43.7°F (6.5°C). Saint Johns notes an average high-temperature of a frosty 43.7°F (6.5°C) in February, hardly diverging from January. Weather in February »Weather in March
March, the first month of the spring in Saint Johns, is a fresh month, with an average temperature fluctuating between 55°F (12.8°C) and 38.7°F (3.7°C). March brings a temperature change, with average high-temperatures moving from February's chilly 43.7°F (6.5°C) to a fresh 55°F (12.8°C). Weather in March »Weather in April
April is a refreshing spring month in Saint Johns, Illinois, with an average temperature varying between 48.4°F (9.1°C) and 66°F (18.9°C). In Saint Johns, stepping into April brings a temperature increase, moving up from March's fresh 55°F (12.8°C) to an enjoyable 66°F (18.9°C). Weather in April »Weather in May
May, the last month of the spring in Saint Johns, is a warm month, with an average temperature varying between 58.1°F (14.5°C) and 75.4°F (24.1°C). May's onset is marked by a temperature increase, moving from a refreshing 66°F (18.9°C) in April to a warm 75.4°F (24.1°C). Weather in May »Weather in June
June, the first month of the summer in Saint Johns, is also a moderately hot month, with an average temperature ranging between max 84.6°F (29.2°C) and min 66.6°F (19.2°C). Saint Johns sees an increase in the average high-temperature with the arrival of June, moving from May's 75.4°F (24.1°C) to a still warm 84.6°F (29.2°C). Weather in June »Weather in July
July is a tropical summer month in Saint Johns, Illinois, with temperature in the range of an average high of 87.3°F (30.7°C) and an average low of 68.7°F (20.4°C). Saint Johns's July weather, marked by an average high temperature of 87.3°F (30.7°C) and an average low temperature of 68.7°F (20.4°C), is the warmest in the year. July's average heat index is calculated to be a sweltering 102.2°F (39°C). Weather in July »Weather in August
August, the last month of the summer in Saint Johns, is another warm month, with temperature in the range of an average low of 66°F (18.9°C) and an average high of 85.5°F (29.7°C). Saint Johns's transition from July to August introduces an average high-temperature of a warm 85.5°F (29.7°C), marking an insignificant variation from the 87.3°F (30.7°C). Weather in August »Weather in September
The first month of the autumn, September, is still a warm month in Saint Johns, Illinois, with an average temperature ranging between min 60.1°F (15.6°C) and max 79.7°F (26.5°C). With the beginning of September, the average high-temperature shows a small decrease, transitioning from a warm 85.5°F (29.7°C) in August to a still moderately hot 79.7°F (26.5°C). Weather in September »Weather in October
October, like September, in Saint Johns, Illinois, is another comfortable autumn month, with an average temperature varying between 49.3°F (9.6°C) and 67.1°F (19.5°C). A subtle decrease in the average high-temperature marks October, falling from September's moderately hot 79.7°F (26.5°C) to a comfortable 67.1°F (19.5°C). Weather in October »Weather in November
November, the last month of the autumn in Saint Johns, is another cool month, with an average temperature varying between 38.3°F (3.5°C) and 53.6°F (12°C). In November, the average high-temperature decreases from a comfortable 67.1°F (19.5°C) in October to a fresh 53.6°F (12°C). Weather in November »Weather in December
December, the first month of the winter in Saint Johns, is still a chilly month, with an average temperature varying between 31.1°F (-0.5°C) and 43.5°F (6.4°C). The start of December comes with a reduction in the average high-temperature, receding from a cool 53.6°F (12°C) in November to a chilly 43.5°F (6.4°C). Weather in December »Updated: Aug 19, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
January, marked by an average high-temperature of 38.8°F (3.8°C) and a low-temperature of 25.7°F (-3.5°C), is the coldest month.
January is the month with the least rainfall. Rain falls for 8.4 days and accumulates 1.5" (38mm) of precipitation.
In Saint Johns, during the entire year, the rain falls for 147.6 days and collects up to 29.17" (741mm) of precipitation.
January through April, November and December are months with snowfall.
In Saint Johns, during the entire year, snow falls for 18 days and aggregates up to 4.53" (115mm) of snow.
The month with the least sunshine is January, with an average of 4.6h of sunshine.
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2.
The month with the most snowfall is February, when snow falls for 5.1 days and typically aggregates up to 1.5" (38mm) of snow.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Saint Johns, and the time zone changes from CST to CDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from CDT to CST.
April is the month with the most rainfall. Rain falls for 15.1 days and accumulates 3.58" (91mm) of precipitation.
The most humid month is May, with an average relative humidity of 79%.
In Saint Johns, snow does not fall in May through October.
With an average of 14h and 48min of daylight, June has the longest days of the year.
The months with the highest UV index are June through August, with an average maximum UV index of 6.
With an average high-temperature of 87.3°F (30.7°C) and an average low-temperature of 68.7°F (20.4°C), July is the warmest month.
The month with the most sunshine is July, with an average of 10.5h of sunshine.
October is the least humid month, with an average relative humidity of 71%.
The month with the shortest days is December, with an average of 9h and 36min of daylight.
Average temperature
Saint Johns, IL
The warmest month (with the highest average high temperature) is July (87.3°F).
The month with the lowest average high temperature is January (38.8°F).
The month with the highest average low temperature is July (68.7°F).
The coldest month (with the lowest average low temperature) is January (25.7°F).
Average pressure
Saint Johns, IL
- Average pressure in January:
30.16"Hg - Average pressure in February:
30.12"Hg - Average pressure in March:
30.08"Hg - Average pressure in April:
29.95"Hg - Average pressure in May:
29.96"Hg - Average pressure in June:
29.93"Hg
- Average pressure in July:
29.98"Hg - Average pressure in August:
29.98"Hg - Average pressure in September:
30.03"Hg - Average pressure in October:
30.04"Hg - Average pressure in November:
30.14"Hg - Average pressure in December:
30.14"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed
Saint Johns, IL
- Average wind speed in January:
9.6mph - Average wind speed in February:
9.6mph - Average wind speed in March:
9.4mph - Average wind speed in April:
9.3mph - Average wind speed in May:
7.8mph - Average wind speed in June:
6.7mph
- Average wind speed in July:
5.8mph - Average wind speed in August:
5.8mph - Average wind speed in September:
6.3mph - Average wind speed in October:
8mph - Average wind speed in November:
8.7mph - Average wind speed in December:
8.9mph
The windiest months (with the highest average wind speed) are January and February (9.6mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).
Average humidity
Saint Johns, IL
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall
Saint Johns, IL
- Average rainfall in January:
1.5" - Average rainfall in February:
1.54" - Average rainfall in March:
2.56" - Average rainfall in April:
3.58" - Average rainfall in May:
3.27" - Average rainfall in June:
3.31"
- Average rainfall in July:
3.07" - Average rainfall in August:
2.8" - Average rainfall in September:
1.73" - Average rainfall in October:
2.36" - Average rainfall in November:
1.89" - Average rainfall in December:
1.57"
The wettest month (with the highest rainfall) is April (3.58").
The driest month (with the least rainfall) is January (1.5").
Average rainfall days
Saint Johns, IL
- Average rainfall days in January:
8.4 days - Average rainfall days in February:
8.3 days - Average rainfall days in March:
14.4 days - Average rainfall days in April:
15.1 days - Average rainfall days in May:
17 days - Average rainfall days in June:
15.1 days
- Average rainfall days in July:
16.3 days - Average rainfall days in August:
14 days - Average rainfall days in September:
11.6 days - Average rainfall days in October:
9.9 days - Average rainfall days in November:
9.3 days - Average rainfall days in December:
8.2 days
The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is December (8.2 days).
Average snowfall
Saint Johns, IL
The month with the highest snowfall is February (1.5").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days
Saint Johns, IL
- Average snowfall days in January:
5.4 days - Average snowfall days in February:
5.1 days - Average snowfall days in March:
2.1 days - Average snowfall days in April:
0.5 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0.1 days - Average snowfall days in November:
1.1 days - Average snowfall days in December:
3.7 days
The month with the highest number of snowfall days is January (5.4 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight / Average sunshine
Saint Johns, IL
- Average daylight in January:
9h and 54min - Average daylight in February:
10h and 48min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 12min - Average daylight in May:
14h and 12min - Average daylight in June:
14h and 48min
- Average daylight in July:
14h and 30min - Average daylight in August:
13h and 36min - Average daylight in September:
12h and 24min - Average daylight in October:
11h and 12min - Average daylight in November:
10h and 6min - Average daylight in December:
9h and 36min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in January:
4h and 36min - Average sunshine in February:
4h and 42min - Average sunshine in March:
6h and 24min - Average sunshine in April:
8h and 30min - Average sunshine in May:
9h and 12min - Average sunshine in June:
10h and 24min
- Average sunshine in July:
10h and 30min - Average sunshine in August:
10h and 6min - Average sunshine in September:
9h and 12min - Average sunshine in October:
6h and 24min - Average sunshine in November:
5h and 30min - Average sunshine in December:
4h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days
Saint Johns, IL
- Average sunshine days in January:
18.1 days - Average sunshine days in February:
15 days - Average sunshine days in March:
13.8 days - Average sunshine days in April:
12.4 days - Average sunshine days in May:
11.4 days - Average sunshine days in June:
12.1 days
- Average sunshine days in July:
12 days - Average sunshine days in August:
14.7 days - Average sunshine days in September:
16.7 days - Average sunshine days in October:
19.5 days - Average sunshine days in November:
19.5 days - Average sunshine days in December:
19.2 days
The months with the most sunshine days are October and November (19.5 days).
The month with the least sunshine days is May (11.4 days).
Average UV index
Saint Johns, IL
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover
Saint Johns, IL
The months with the most cloud cover are January and February (Cloud cover 50).
The month with the least cloud cover is June (Cloud cover 28).
Average visibility
Saint Johns, IL
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
